The long-term goal of this research is to develop life course models for youth at high risk of contracting HIV and to use those models to carefully target malleable risk and protective mediators in preventive interventions. The objectives of this application are to identify (a) social network risk characteristics and social network protective characteristics, (b) personal psychological reources, and (c) participation in general normative activities and service ultilization that are associated with youths' HIV risk behavior using a sample of 300 homeless and runaway youth. Specific aim one is to use OLS regression to identify empirically the direct association between social network characteristics and HIV risk behaviors in a Midwestern sample of homeless and runaway youth. The second aim is to determine whether participation in general normative activites and service utilization uniquely protect homeless youth and mediate the relations between social network characteristics and HIV risk behaviors. Aim three is to empirically examine whether personal psychological resources (e.g., self-control, self-efficacy, self-esteem) moderate or buffer the relations between social network characteristics and HIV risk behaviors. Aim four is to identify whether gender, race/ethnicity, and sexual orientation moderate relations between social networks and HIV risk behaviors. Finally, aim five is to utilize qualitative methods to conduct interviews with a sub-sample of homeless and runaway youth to develop an in-depth understanding of the behaviors and patterns that are associated with variations in the size and composition of social networks (as determined from the baseline interview). The next step will be to recruit and interview 300 homeless and runaway youth, ages 14 to 21, through three service agencies. In addition, we will conduct 40 in-depth qualitative interviews (i.e., approximately 13 per agency/city). [unreadable] [unreadable] [unreadable] [unreadable]